Various military organizations, in recent years, have been interested in laser locator systems. One such system has been designed to warn armored vehicle crews when they are being designated by a 1.06 micrometer laser designater or rangefinder. The system indicates which quadrant the threat is in and a narrow view detector indicates when the vehicle's main tube is within a few degrees of the target. At this point, the threat can be found by using the vehicle's night sight and appropriate countermeasure can be initiated. Another proposed system utilizes interferometry to detect the presence of a laser beam, its wavelength and its angle of incidence.
The device of the present invention utilizes a triangular cube corner reflector equipped with three detector arrays and electronic processor. The device operates when a bundle of parallel light rays (cw or pulse) illuminates the entire corner entrance aperture. The usefulness of the invention can be divided into two areas of application: Case A, where it determines the location of remote laser rediation (i.e., angle of arrival meter), and case B, where the spatial orientation of a moving object is to be determined, (i.e., guidance system applications).
Case A. The position of the corner has to be known, or can serve as the reference. When the plane of the aperture is vertical, the horizontal and vertical aspect angles of the laser source can be determined, with this data a rangefinder can be employed, to measure the location of the transmitter. This device can be operated either as an airborne or ground based system. It will serve the following purposes:
(a) Position finding (Distance, horizontal and vertical aspect angles). PA1 (b) Warning system. With the position information of (a), the following actions may occur: PA1 (1) evasion, PA1 (2) screen the threatened position with smoke in the line-of-sight, PA1 (3) start counter measures such as gunfire, to disable or destroy the illumination source. PA1 (a) Alignment of remote objects. PA1 (b) Communication--position and movement of friendly vehicles and objects, directional message and coded commands. PA1 (c) Controlled landing of airplanes etc. PA1 (d) Guidance of vehicles, airplanes etc., moving on the ground, at night, or in adverse weather conditions (fog, smoke). PA1 (e) Device for the measurement of atmospheric turbulence along certain propagation paths, measuring in both directions simultaneously. Angle of arrival fluctuation meter. PA1 (f) Rescue mission, etc.
Case B. For the position determination of moving objects at remote distances, on the ground or in the air, the direction of the received laser beam, and its length, will be the reference. The corner will be mounted on the object exposed to the laser beam. Then the position of the corner can be measured, and the data can be processed by ground equipment or by appropriate processing components on board the object. Corrections of the object's position can be initiated if necessary. When we can illuminate the object for a certain length of time with a laser beam, the position of the object can be determined with respect to its direction of movement. If the object is a missile, and rotation is involved, the technique is still applicable, and the rate of rotation can be determined. When the exhaust gases of the missile cannot be penetrated by the laser light, three corner devices may be necessary on board the missile. They should be placed 120.degree. apart, as far away as possible from the missile axis. When the missile rolls, at least one corner should always be outside the region of gases. In case B, the invention will serve the following purposes:
For this purpose corner reflectors have been used as retroreflectors for radar radiation since WW II. It is still a big problem to find a small boat in a rough sea, or persons lost in wilderness and in the mountains, etc. When a helicopter, for example, is equipped with the device under consideration here, and the people in need have a small laser, the rescue action could be made more effective.